Wax emulsion compositions, and particularly wax-in-water emulsions, are well known standard articles of commerce which have many uses. One of the more widely known applications of wax-in-water emulsions is that of a polishing composition. Polishing compositions can be applied to wood, leather, floor tiles, automobile finishes, household appliances and many other articles whose appearance can be enhanced by a coating of wax. Also, wax-in-water emulsion compositions (hereinafter referred to as wax emulsions) have been shown to be suitable for use in the preparation of paper products, textiles and many other articles of commerce.
More recently, newly developed wax emulsions have been disclosed to be particularly suitable for regulation of transpiration of growing plants. U.S. Pat. Nos. 3,410,678, issued Nov. 2, 1968 and 3,388,992, issued June 18, 1968 disclose specific wax emulsion compositions, particularly effective as anti-transpirants when applied to growing plants.
One problem normally encountered when using wax emulsions is their inherent lack of stability. Unstabilized wax emulsions often break and separate into a liquid phase and a solid phase or sometimes become a gel or a thick viscous cream which will not flow and thus lose their liquid characteristics. These undesirable effects of wax emulsion instability can occur as a result of storage, shipping or alternate freezing and thawing of the liquid emulsion. Freezing and thawing most often occur during shipping or storage in colder climates where the emulsion is sometimes exposed to temperatures well below the freezing point of water. The term "freeze-thaw cycle" designates a procedure wherein the liquid emulsions is exposed to temperatures below the freezing point of the emulsion for a period of time sufficient for the emulsion to be frozen to a hard solid mass. Thereafter the frozen emulsion is subject to a temperature above its freezing point for a period of time sufficient to thaw the entire emulsion. Normally, when a wax emulsion is exposed to a freeze-thaw cycle, the emulsion thickens to a non-flowable, gel-like composition which can no longer be handled in apparatus designed for flowable liquids. For this reason, it is not uncommon to see containers of wax emulsions labelled with the warning "KEEP FROM FREEZING".
Wax emulsions usually are prepared as concentrates having 20 to 60 weight percent wax, 1 to 10 weight percent emulsifying agents with the rest of the composition being made up of water and additives including oil, stabilizers, fungicides, insecticides, etc. The wax emulsion is normally packaged and shipped by the manufacturer in a concentrate form preferably containing 40 to 60 weight percent wax. The concentrate emulsion if desired can be easily diluted to a lower wax-in-water ratio by the customer using the product by simply adding more water to the concentrate. Concentrations as low as 0.1 to 10 weight percent wax-in-water are not uncommon in many applications.
For most customer applications, a thin flowable homogeneous liquid emulsion is the desired form. Unstabilized wax-in-water emulsions which have gelled or have become a thich viscous cream as a result of instability are usually unsuitable for practical use, because they are difficult to disperse in water. Therefore, it is advantageous to provide a stable wax emulsion which will not break, thicken, gel or cream when subject to freeze-thaw cycles or other conditions which result in emulsion breakdown.
We have now discovered new improved wax emulsions and methods of their preparation which provide compositions having improved emulsion stability characteristics. As hereinafter given all parts and percentages are by weight unless otherwise specified.